fstream io problems with GLUT

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Hi
I''m reading pixel data with glReadPixels while using glut, I want to save the array of pixel data in a text format in a file using fstream. fstream will create the file but will not actually write the data to a file from within glutmainloop do you know why? and how to fix it?
code:
/*the func below is called from glutKeyboardFunc*/
void send_image_data_to_text(void)
{
RGB value;
int x,y;
fstream examplefile ("pmg.txt",ios::out);
if (examplefile.is_open())
{
examplefile << "This is a line2.\n";
examplefile << "This is another line.\n";
examplefile.close();
cout << "ha";
for(x=0; x<70; x++)
for(y=0; y<70; y++)
{
value = pic[0].getPixel(x, y);
examplefile << value.r << value.g << value.b;
examplefile << "fuck!";
cout << value.r << value.g << value.b;
}
examplefile.close();
}
}
this function works fine in a normal VC++ project or in main before glutmainloop is called. This is how I know there is a problem between fstream and glut.
If you have any info I would love to here from you.